Which tools in what order knowing what you do now?

I'm sure this question has been asked in different forms but here goes.......

If you knew then (when you first started dabbling in SEO), what you know now......

What tools would you buy and learn first.

What tools did you buy that you ended up duplicating (buying other tools for another purpose and finding out they made the first tool purchase obsolete(or accomplished the same task)) meaning you spent money twice for one purpose?

This may help others NOT buy what they're NOT ready for at an early stage of development or buy tools they just don't really need.

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